My suggestion is a mod where every part that generates, stores or uses electric charge has a tweakable in the VAB that assigns that part to a category or 'bus'. These parts will then only interact with other parts in that bus or category. This way you can for example, assign your biggest solar panels and your ion drives to the Main Bus, have your reaction wheels and some smaller panels assigned to Aux Bus 1 so you still have some control authority, and perhaps have an RTG powering your remote tech antenna on Aux Bus 2. Or another example, have an ISRU and drills running on a separate bus to your life support on your surface base. This way all your important systems will be running and you're heavy applications can run full power, regardless of whether they run dry or not. Also making for some interesting planning and building in the VAB.